Wireless power transmitters and receivers, and method for permitting a wireless power receiver by a wireless power transmitter

ABSTRACT

An apparatus and method are provided for permitting a wireless power receiver to be charged by a wireless power transmitter. The method includes generating a Power Receiving Unit (PRU) control signal including permission information indicating charging permission for the wireless power receiver; and transmitting the PRU control signal to the wireless power receiver.

PRIORITY

This application claims priority under 35 U.S.C. §119(a) to KoreanPatent Application Serial Nos. 10-2012-0116392 and 10-2013-0050308,which were filed in the Korean Intellectual Property Office on Oct. 19,2012 and May 3, 2013, respectively, the entire disclosure of each ofwhich is hereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to a wireless charging network,and more particularly, to wireless power transmitter and receivers, anda method for permitting, by a wireless power transmitter, a wirelesspower receiver for charging in a wireless charging network.

2. Description of the Related Art

Mobile terminals, such as cell phones, Personal Digital Assistants(PDAs), etc., are powered by rechargeable batteries, and often useseparate charging devices to recharge these batteries.

Typically, a charging device and a battery, each having contactingterminals on an outer surface thereof, are electrically connected byconnecting their contacting terminals to each other. However, when usinga contact charging method, the contacting terminals are oftencontaminated with dirt or rust, leading to inappropriate batterycharging.

To address this problem, wireless charging or contactless chargingtechnologies have been developed and applied to many differentelectronic devices. For example, using wireless charging, a battery of acell phone is automatically charged by placing the cell phone on acharging pad, without using a separate charging connector.

Examples of wireless charging technology include an electromagneticinduction method using coils, a resonance method using resonance, and aRadio Frequency (RF)/microwave radiation method that converts electricalenergy into microwaves for transmission.

The method based on electromagnetic induction transfers power betweenprimary and secondary coils. More specifically, moving a magnet around acoil produces an induced current, based on which a magnetic field isproduced at a transmission end. The change in the magnetic field at areceiving end induces a current to generate energy. This phenomenon iscommonly referred to as “magnetic induction,” and the wireless powertransmission method based on the magnetic induction provides superiorenergy transmission efficiency.

In the resonance method using resonance, resonant electrical energy ofelectromagnetic waves is directly transferred only to a device having asame resonant frequency, and a non-used part of the energy isre-absorbed into the magnetic field, rather than being dispersed in theair. Consequently, the resonant electrical energy is not deemed harmfulto surrounding machines or bodies.

Although studies on the various wireless charging methods have recentlybeen done, standards for prioritizing wireless charging, searching forwireless power transmitters/receivers, selecting the communicationfrequency between the wireless power transmitter and receiver, adjustingthe wireless power, selecting a matching circuit, distributingcommunication time for each wireless power receiver in a single chargingcycle, etc., have not yet been suggested.

SUMMARY OF THE INVENTION

Accordingly, the present invention is designed to address at least theproblems and/or disadvantages described above and to provide at leastthe advantages described below.

An aspect of the present invention is to provide wireless powertransmitters and receivers, and a method for a wireless powertransmitter to permit a wireless power receiver for charging.

Another aspect of the present invention is to provide a method for awireless power transmitter to notify at least one wireless powerreceiver in a charging network whether it is permitted to be wirelesslycharged.

In accordance with an aspect of the present invention, a method isprovided for permitting a wireless power receiver to be wirelesslycharged by a wireless power transmitter. The method includes addinginformation about charging permission for the wireless power receiver toa Power Receiving Unit (PRU) control signal for controlling the wirelesspower receiver; and transmitting the PRU control signal to the wirelesspower receiver.

In accordance with another aspect of the present invention, a method isprovided for determining permission, by a wireless power receiver, to becharged by a wireless power transmitter. The method includes receiving,from the wireless power transmitter, a PRU control signal includinginformation indicating that the wireless power receiver is permitted tobe charged; confirming the information; displaying a message on a screenasking whether to be on standby; generating a PRU reporting signalincluding information indicating whether the wireless power receiver isto be on standby for charging; and transmitting the PRU reporting signalto the wireless power transmitter.

In accordance with another aspect of the present invention, a wirelesspower transmitter is provided for permitting a wireless power receiverfor wireless charging. The wireless power transmitter includes a powertransmitter for transmitting charging power to the wireless powerreceiver; a controller for generating a Power Receiving Unit (PRU)control signal including information about charging permission for thewireless power receiver; and a communication unit for transmitting thePRU control signal to the wireless power receiver.

In accordance with another aspect of the present invention, a wirelesspower receiver is provided for determining permission to be charged by awireless power transmitter. The wireless power receiver includes a powerreceiver for receiving wireless charging power from the wireless powertransmitter; a communication unit for receiving from the wireless powertransmitter a Power Receiving Unit (PRU) control signal includinginformation indicating that the wireless power receiver is permitted tobe charged; a display unit for confirming the information and displayinga message on a screen asking whether to be in a standby state; and acontroller for generating a PRU reporting signal including informationindicating whether the wireless power receiver is in the standby forcharging and sending the PRU reporting signal to the wireless powertransmitter via the communication unit.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features, and advantages of certainembodiments of the present invention will become more apparent from thefollowing detailed description taken in conjunction with reference tothe accompanying drawings, in which:

FIG. 1 illustrates a wireless charging system, according to anembodiment of the present invention;

FIG. 2 is a block diagram illustrating a wireless power transmitter anda wireless power receiver, according to an embodiment of the presentinvention;

FIG. 3 is a block diagram illustrating a wireless power transmitter anda wireless power receiver, according to an embodiment of the presentinvention;

FIG. 4 is a signal flow diagram illustrating operations of a wirelesspower transmitter and a wireless power receiver, according to anembodiment of the present invention;

FIG. 5 is a flowchart illustrating operations of a wireless powertransmitter and wireless power receiver, according to an embodiment ofthe present invention;

FIG. 6 illustrates histograms of amounts of power applied by a wirelesspower transmitter over time;

FIG. 7 is a flowchart illustrating a method of controlling a wirelesspower transmitter, according to an embodiment of the present invention;

FIG. 8 illustrates histograms of amounts of power applied by a wirelesspower transmitter, according to an embodiment of the present invention;

FIG. 9 is a flowchart illustrating a method of controlling a wirelesspower transmitter, according to an embodiment of the present invention;

FIG. 10 illustrates histograms of amounts of power applied by a wirelesspower transmitter, according to an embodiment of the present invention;

FIG. 11 is a block diagram illustrating a wireless power transmitter anda wireless power receiver, according to an embodiment of the presentinvention;

FIG. 12 is a signal flow diagram illustrating a permission procedurebetween a wireless power transmitter and a wireless power receiver,according to an embodiment of the present invention;

FIG. 13 is a flowchart illustrating an operating process of a wirelesspower transmitter, according to an embodiment of the present invention;

FIG. 14 is a flowchart illustrating an operating process of a wirelesspower receiver, according to an embodiment of the present invention;

FIG. 15 illustrates a standby screen of a wireless power receiver,according to an embodiment of the present invention; and

FIG. 16 is a signal flow diagram illustrating a permission procedurebetween a wireless power transmitter and a wireless power receiver,according to an embodiment of the present invention.

Throughout the drawings, like reference numerals will be understood torefer to like parts, components, and structures.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

Various embodiments of the present invention will now be described indetail with reference to the accompanying drawings. In the followingdescription, specific details such as detailed configuration andcomponents are merely provided to assist the overall understanding ofthese embodiments of the present invention. Therefore, it should beapparent to those skilled in the art that various changes andmodifications of the embodiments described herein can be made withoutdeparting from the scope and spirit of the present invention. Inaddition, descriptions of well-known functions and constructions areomitted for clarity and conciseness.

FIG. 1 illustrates a wireless charging system, according to anembodiment of the present invention.

Referring to FIG. 1, the wireless charging system includes a wirelesspower transmitter 100 and wireless power receivers 110-1, 110-2, . . .110-n. The wireless power receivers 110-1, 110-2, . . . 110-n may beincluded in mobile communication terminals, PDAs, Portable MultimediaPlayers (PMPs), smartphones, etc. The wireless power transmitter 100wirelessly transmits power 1-1, 1-2, . . . 1-n to the wireless powerreceivers 110-1, 110-2, . . . 110-n, which are wireless power receiversauthenticated for charging via a predetermined authentication procedure.For example, the wireless power transmitter 100 transmits the wirelesspower to the wireless power receivers 110-1, 110-2, . . . 110-n in anelectromagnetic waveform.

The wireless power transmitter 100 may also perform bidirectionalcommunication with the wireless power receivers 110-1, 110-2, . . .110-n. The wireless power transmitter 100 and the wireless powerreceiver 110-1, 110-2, . . . 110-n process and transmit/receive packets201, 202, . . . 2-n including certain frames, which will be describedbelow in more detail.

When the wireless power transmitter 100 uses the above-describedresonance method to wirelessly transmit power to the wireless powerreceivers 110-1, 110-2, . . . 110-n, a distance between the wirelesspower transmitter 100 and the wireless power receivers 110-1, 110-2, . .. 110-n may be 30 m or less. However, when the wireless powertransmitter 100 uses the above-described electromagnetic inductionmethod to wirelessly transmit power to the wireless power receivers110-1, 110-2, . . . 110-n, a distance between the wireless powertransmitter 100 and the wireless power receivers 110-1, 110-2, . . .110-n may be 10 cm or less.

The wireless power receivers 110-1, 110-2, . . . 110-n each charge abattery therein using the wireless power received from the wirelesspower transmitter 100. The wireless power receivers 110-1, 110-2, . . .110-n may also transmit to the wireless power transmitter 100 a signalto request the wireless power transmission, information for the wirelesspower reception, information of a state of the wireless power receiver,and/or control information of the wireless power transmitter, which willbe described below in more detail.

The wireless power receivers 110-1, 110-2, . . . 110-n may also transmita message indicating a respective charging state to the wireless powertransmitter 100.

The wireless power transmitter 100 may include a display which displaysthe respective states of the wireless power receivers 110-1, 110-2, . .. 110-n, based on messages received from the wireless power receivers110-1, 110-2, . . . 110-n. The wireless power transmitter 100 may alsodisplay an estimate of the time until the charging the respectivewireless power receivers 110-1, 110-2, . . . 110-n is complete.

The wireless power transmitter 100 may also transmit a control signal toeach of the wireless power receivers 110-1, 110-2, . . . 110-n todisable the wireless charging function. When receiving the disablesignal from the wireless power transmitter 100, each of the wirelesspower receivers 110-1, 110-2, . . . 110-n disables its own wirelesscharging function.

FIG. 2 is a block diagram illustrating a wireless power transmitter anda wireless power receiver, according to an embodiment of the presentinvention.

Referring to FIG. 2, the wireless power transmitter 200 includes a powertransmitter 211, a controller 212, and a communication unit 213. Thewireless power receiver 250 includes a power receiver 251, a controller252, and a communication unit 253.

The power transmitter 211 wirelessly transmits power to the wirelesspower receiver 250. Herein, the power transmitter 211 may supply powerin an Alternate Current (AC) waveform, or may convert power in a DirectCurrent (DC) form into an AC waveform for supply by using an inverter.The power transmitter 211 may include a built-in battery or a powerreceiving interface for receiving power from an outside, e.g., anoutlet, and supplying power to other components in the wireless powertransmitter 200. A person of ordinary skill in the art will readilyunderstand that the power transmitter 211 is not limited thereto, butmay be implemented by any device capable of wirelessly providing powerin an AC waveform.

In addition, the power transmitter 211 may provide the AC power inelectromagnetic waves to the wireless power receiver 250. The powertransmitter 211 may further include a resonance circuit for transmittingor receiving certain electromagnetic waves.

When the power transmitter 211 includes the resonance circuit, aninductance L of a loop coil of the resonance circuit may vary. A personof ordinary skill in the art will readily understand that the wirelesstransmitter 211 is not limited thereto, but may be implemented by anydevice capable of transmitting or receiving electromagnetic waves.

The controller 212 controls general operations of the wireless powertransmitter 200. To control general operations of the wireless powertransmitter 200, the controller 212 may use a control algorithm, aprogram, or an application read from a storage (not shown). For example,the controller 212 may be implemented in the form of a centralprocessing unit (CPU), a microprocessor, or a mini-computer.

The communication unit 213 communicates with the wireless power receiver250 in a predetermined communication method. For example, thecommunication unit 213 may communicate with the communication unit 253of the wireless power receiver 250 using Near Field Communication (NFC),Zigbee communication, infrared communication, ultraviolet communication,BlueTooth (BT) communication, Bluetooth Low Energy (BLE), etc.Additionally, the communication unit 213 may use the Carrier SenseMultiple Access/Collision Avoidance (CSMA/CA) algorithm.

Additionally, the communication unit 213 transmits an information signalof the wireless power transmitter 200, e.g., through unicasting,multicasting, or broadcasting.

The communication unit 213 receives power information from the wirelesspower receiver 250. For example, the power information may include atleast one of a capacity of the wireless power receiver 250, remainingbattery power, frequency of charging, battery consumption, batterycapacity, and battery charge/consumption ratio.

The communication unit 213 transmits a charging function control signalto control a charging function of the wireless power receiver 250. Thecharge function control signal enables or disables the charging functionby controlling the power receiver 251 of the wireless power receiver250. Alternatively, the power information may include information aboute.g., insertion of a wired charging terminal, change from SA mode to NSAmode, release from an error condition, etc.

The communication unit 213 may receive signals from the wireless powerreceiver 250 and also from different wireless power transmitters. Forexample, the communication unit 213 may receive a Notice signal having aframe as shown in Table 1, from the different wireless powertransmitter.

Alternatively, the power transmitter 211 and the communication unit 213may be integrated in a single hardware device, and thus, the wirelesspower transmitter 200 may use in-band communications.

As described above, the wireless power transmitter 200 and the wirelesspower receiver 250 communicate various signals with each other.Therefore, subscription of the wireless power receiver 250 to a wirelesspower network hosted by the wireless power transmitter 200 and acharging process through the wireless power network may be performed.

FIG. 3 is a block diagram illustrating a wireless power transmitter anda wireless power receiver, according to an embodiment of the presentinvention.

Referring to FIG. 3, the wireless power transmitter 200 includes a powertransmitter 211, a controller and communication unit 212, 213, a drivingunit 214, an amplifier, and a matching unit 216. The wireless powerreceiver 250 includes a power receiver 251, a controller andcommunication unit 252, 253, a rectifier 254, a DC-to-DC converter 255,a switching unit 256, and a loading unit 257.

The driving unit 214 outputs DC power with a preset voltage. The voltagevalue of the DC power output from the driving unit 214 may be controlledby the controller and communication unit 212, 213.

The DC current output by the driving unit 214 flows to the amplifier215, which amplifies the DC current with a preset gain. The amplifier215 may also convert the DC power to AC power based on a signal inputfrom the controller and communication unit 212, 213. Accordingly, theamplifier 215 outputs the AC power.

The matching unit 216 performs impedance matching. For example, thematching unit 216 controls output power to be highly efficient or outputby adjusting impedance viewed from the matching unit 216. The matchingunit 216 adjusts impedance under control of the controller andcommunication unit 212, 213. For example, the matching unit 216 includesat least one of coils and capacitors. The controller and communicationunit 212, 213 controls a state of connection with at least one of thecoil and capacitor, and do impedance matching accordingly.

The power transmitter 211 transmits the AC power to the power receiver251. In FIG. 3, the power transmitter 211 and the power receiver 251 areimplemented as resonant circuits having a same resonant frequency. Forexample, the resonant frequency may be 6.78 MHz.

The controller and communication unit 212, 213 communicate with thecontroller and communication unit 252, 253 of the wireless powerreceiver 250, e.g., using bidirectional Wireless Fidelity (WiFi),Zigbee, or BT/BLE at 2.4 GHz.

The power receiver 251 receives the wireless charging power.

The rectifier 254, which may be implemented, for example, with bridgediodes, rectifies the received wireless power into a DC form. TheDC-to-DC converter 255 converts the rectified power to have apredetermined gain. For example, the DC-to-DC converter 255 converts therectified power to 5 V. Minimum and maximum values of a voltage that maybe applied to the input end of the DC-to-DC converter 255 may bepredetermined.

The switching unit 256 connects the DC-to-DC converter 255 to theloading unit 257 and keeps an ON or OFF state under control of thecontroller 252. The loading unit 257 may store the converted power inputfrom the DC-to-DC converter 255 when the switching unit 256 is in the ONstate.

FIG. 4 is a signal flow diagram illustrating operations of a wirelesspower transmitter and a wireless power receiver, according to anembodiment of the present invention.

Referring to FIG. 4, a wireless power transmitter 400 powers up in stepS401, and sets configurations in step S402.

In step S403, the wireless power transmitter 400 enters a power savemode, in which the wireless power transmitter 400 may apply differentpower beacons for detection for their respective periods. The wirelesspower transmitter 400 applies power beacons for detection at powervalues that may or may not be different, in steps 404 and 405. Some orall of the power beacons for detection may have sufficient amounts ofpower to drive a communication unit of a wireless power receiver 450.For example, the wireless power receiver 450 may communicate with thewireless power transmitter 400 by driving the communication unit withsome or all of the power beacons. Herein, this state may be denoted as anull state.

The wireless power transmitter 400 may detect a load change due to theentrance of the wireless power receiver 450 into the wireless powernetwork of the wireless power transmitter 400.

In step S408, the wireless power transmitter 400 enters a low powermode.

In step S409, the wireless power receiver 450 powers up with powerreceived from the wireless power transmitter 400 and then drives itscommunication. In step S410, the wireless power receiver 450 transmits aPower Transmitting Unit (PTU) search signal, which is a signal to searchfor a wireless power transmitter. For example, the wireless powerreceiver 450 may transmit the PTU search signal in a BLE basedAdvertisement signal. Additionally, the wireless power receiver 450 mayperiodically transmit the PTU search signal, until a response from thewireless power transmitter 400 is received or expiration of apredetermined time.

Having received the PTU searching signal from the wireless powerreceiver 450, the wireless power transmitter 400 transmits a PowerReceiving Unit (PRU) response signal in step S411. The PRU responsesignal forms a connection between the wireless power transmitter 400 andthe wireless power receiver 450.

In step S412, the wireless power receiver 450 transmits a PRU staticsignal to the wireless power transmitter 400. The PRU static signalindicates a state of the wireless power receiver 450.

In step S413, the wireless power transmitter 400 transmits a PTU staticsignal to the wireless power receiver. The PTU static signal indicates acapability of the wireless power transmitter 400.

In steps S414 and S415, the wireless power receiver 450 periodicallytransmits a PRU dynamic signal. The PRU dynamic signal includesinformation about at least one parameter measured in the wireless powerreceiver 450. For example, the PRU dynamic signal may includeinformation about a voltage at an output end of a rectifier of thewireless power receiver 450. Herein, this state of the wireless powerreceiver 450 may be denoted as a boot state S407.

In step S416, the wireless power transmitter 400 enters a power transfermode, and in step S417, transmits a PRU control signal, i.e., a commandsignal authorizing the wireless power receiver 450 to be charged. In thepower transfer mode, the wireless power transmitter 400 may transmitcharging power.

The PRU control signal transmitted by the wireless power transmitter 400may include enable/disable information and authorization (or permission)information authorizing the wireless power receiver 450 to be charged.The PRU control signal may be transmitted when the wireless powertransmitter 400 is to change the state of the wireless power receiver450, or may be periodically transmitted, e.g., at 250 ms intervals.

In steps S418 and S419, the wireless power receiver 450 changes itssettings based on the PRU control signal and transmits the PRU dynamicsignal to report the state of the wireless power receiver 450. Forexample, the PRU dynamic signal may include at least one of voltage,current, a state of the wireless power receiver, and temperatureinformation. When transmitting the PRU dynamic signal, this state ofwireless power receiver 450 may be denoted as an ON state.

For example, the PRU dynamic signal may have a data structure as shownin Table 1.

TABLE 1 Field octets description use units Optional fields 1 1 populatedmandatory V_(rect) 2 Voltage at diode mandatory mV output I_(rect) 2Current at diode Mandatory mA output V_(out) 2 Voltage at Optional mVcharge/battery port I_(out) 2 Current at Optional mA charge/battery portTemperature 1 Temperature of Optional Deg C. PRU from −40 C. V_(rect)min dyn 2 V_(rect) low limit optional mV (dynamic value) V_(rect) setdyn 2 Desired V_(rect) optional mV (dynamic value) V_(rect) hign dyn 2V_(rect) high limit optional mV (dynamic value) PRU alert 1 Warningsmandatory Bit field RFU 3 undefined

As shown in Table 1, the PRU dynamic signal may include informationabout an optional field, voltage at the output of the rectifier of thewireless power receiver, current at the output of the rectifier of thewireless power receiver, voltage at the output of the DC-to-DC converterof the wireless power receiver, current at the output of the DC-to-DCconverter of the wireless power receiver, temperature, minimum voltageat the output of the rectifier of the wireless power receiver, optimumvoltage at the output of the rectifier of the wireless power receiver,maximum voltage at the output of the rectifier of the wireless powerreceiver, and a PRU alert.

For example, the PRU alert information may be formed in a data structureas shown in Table 2.

TABLE 2 7 6 5 4 3 2 1 0 over over over charge TA tran- restart RFUvoltage current temper- complete detect sition request ature

As shown in Table 2, the PRU alert information may include an overvoltage field, an over current field, an over temperature field, acharge complete field, a wired charging terminal insertion detect (TAdetect) field, an SA/NSA mode transition field, a restart request field,and a Reserved for Future Use (RFU) field.

The wireless power receiver 450 receives the PRU control signal and thenstarts charging. For example, if the wireless power transmitter 400 hasenough power to charge the wireless power receiver 450, it transmits thePRU control signal to enable the wireless power receiver to be charged.The PRU control signal may be transmitted each time a charging statechanges. Alternatively, the PRU control signal may be transmitted atintervals of 250 ms, or may be transmitted each time there is a changein parameter. The PRU control signal may also be transmitted in apredetermined threshold time, e.g., every second, even if there is nochange in parameter.

Upon detection of an error, the wireless power receiver 450 sends analert signal to the wireless power transmitter in step S420. The alertsignal may be transmitted in the PRU dynamic signal or in the PRU alertsignal. For example, the wireless power receiver 450 may send thewireless power transmitter 400 the alert signal by reflecting an errorcondition in the PRU alert field of Table 3, as shown below.

Alternatively, the wireless power receiver 450 may send the wirelesspower transmitter 400 the alert signal (e.g., the PRU alert signal) toindicate an error condition. Upon reception of the alert signal, thewireless power transmitter 400 enters a latch fault mode in step S422and the wireless power receiver 450 enters into a null state in stepS423.

FIG. 5 is a flowchart illustrating operations of a wireless powertransmitter and a wireless power receiver, according to an embodiment ofthe present invention.

Referring to FIG. 5, the wireless power transmitter powers up in stepS501. In step S503, the wireless power transmitter resets its initialconfiguration. In step S505, the wireless power transmitter enters intoa power save mode. In the power save mode, the wireless powertransmitter may apply different amounts of power to its powertransmitter.

FIG. 6 illustrates histograms of amounts of power applied by a wirelesspower transmitter over time, according to an embodiment of the presentinvention.

For example, as illustrated in FIG. 6, the wireless power transmitterapplies second detection powers 601 and 602 and third detection powers611 to 615 to the power transmitter. More specifically, the wirelesspower transmitter applies the second detection powers 601 and 602 atsecond cycles in a second period of time and applies the third detectionpowers 611 to 615 at third cycles in a third period of time. AlthoughFIG. 6 illustrates the third detection power 611 to 615 having differentvalues, the third detection power 611 to 615 may also have the samevalues. For example, the wireless power transmitter may output the thirddetection power 611 and subsequently the third detection power 612having the same amount of power as that of the third detection power611.

When the wireless power transmitter outputs the same amount of thirddetection power, the amount of third detection power is set to detect asmallest wireless power receiver, e.g., a wireless power receiver ofcategory 1.

However, the wireless power transmitter may output the third detectionpower 611 and subsequently the third detection power 612 having adifferent amount of power from that of the third detection power 611.When the wireless power transmitter outputs different amounts of thirddetection power, each amount of third detection power may be set todetect a wireless power receiver in any of categories 1 to 5.

For example, the third detection power 611 is set high enough to detecta wireless power receiver of category 5, the third detection power 612is set high enough to detect a wireless power receiver of category 3,and the third detection power 613 is set high enough to detect awireless power receiver of category 1.

The second detection powers 601 and 602 are set high enough to drive thewireless power receiver, i.e., to drive the controller and communicationpart of the wireless power receiver.

The wireless power transmitter applies the second detection powers 601and 602 and the third detection powers 611 to 615 to the wireless powerreceiver at second and third cycles, respectively. If the wireless powerreceiver is arranged on the wireless power transmitter, impedance viewedfrom a particular point of the wireless power transmitter may bechanged. The wireless power transmitter may detect the change inimpedance while applying the second detection powers 601 and 602 and thethird detection powers 611 to 615. For example, the wireless powertransmitter may detect the change in impedance while applying the thirddetection power 615.

Accordingly, referring again to FIG. 5, the wireless power transmitterdetects an object in step S507. If an object has not been detected instep S507, the wireless power transmitter maintains the power save mode,wherein different kinds of power are periodically applied, in step S505.

However, if an object has been detected, e.g., by a change in impedance,in step S507, the wireless power transmitter enters a low power mode instep S509. In the low power mode, the wireless power transmitter appliesenough power to drive the controller and communication unit of thewireless power receiver.

For example, referring again to FIG. 6, the wireless power transmitterapplies driving power 620 to the power transmitter. The wireless powerreceiver receives the driving power 620 and drives the controller andcommunication unit. Based on the driving power 620, the wireless powerreceiver communicates with the wireless power transmitter in apredetermined scheme. For example, the wireless power receiver transmitsor receives data authentication, and joins a wireless power networkhosted by the wireless power transmitter based on the data. If a foreignobject is detected, instead of the wireless power receiver, datacommunication is not made.

Thus, referring again to FIG. 5, the wireless power transmitterdetermines whether a foreign object is detected in step S511. Forexample, if the wireless power transmitter has not received any responsefrom an object within a predetermined time, the wireless powertransmitter may determine that the detected object is a foreign object.

Having determined that the object is a foreign object, the wirelesspower transmitter enters a latch fault mode in step S513. However, whenthe object is not a foreign object the wireless power transmitterperforms a joining procedure in step S519.

For example, the wireless power transmitter may periodically apply firstpowers 631 to 634 at first cycles. The wireless power transmitter maydetect a change in impedance while applying the first power.

If the foreign object has been removed in step S515, the wireless powertransmitter may detect the change in impedance and determine that theforeign object has been removed. However, if the foreign object has notbeen removed in step S515, the wireless power transmitter may not detectthe change in impedance and determines that the foreign object has notbeen removed. When the foreign object has not been removed, the wirelesspower transmitter may output an indication, e.g., a lamp flickeringand/or warning sound, to inform the user that the wireless powertransmitter is currently in an error condition.

If it is determined that the foreign object has not been removed in stepS515, the wireless power transmitter maintains the latch fault mode instep S513. However, if the foreign object is determined to have beenremoved in step S515, the wireless power transmitter enters the powersave mode in step S517.

For example, as illustrated in FIG. 6, the wireless power transmittermay apply second powers 651 and 652 and third powers 661 to 665.

As described above, the wireless power transmitter enters the latchfault mode if a foreign object is detected, instead of a wireless powerreceiver. The wireless power transmitter then determines whether theforeign object has been removed, based on a change in impedance at thepower applied in the latch fault mode. Basically, the latch fault modeis entered when a foreign object is placed within a detection range ofthe wireless power transmitter.

However, there may be other various requirements for entering the latchfault mode in accordance with other embodiments of the presentinvention. For example, the wireless power transmitter may enter thelatch fault mode after cross-connecting to the wireless power receiver.A cross-connection occurs when the wireless power transmitter connectswith a wireless power receiver that is already connected to anotherwireless power transmitter

Thus, in cross-connecting between the wireless power transmitter and thewireless power receiver, the wireless power transmitter returns to aninitial state and the wireless power receiver is removed.

FIG. 7 is a flowchart illustrating a method of controlling a wirelesspower transmitter, according to an embodiment of the present invention.

Referring to FIG. 7, the wireless power transmitter powers up in stepS701. In step S703, the wireless power transmitter resets its initialconfiguration. In step S705, the wireless power transmitter enters apower save mode. In the power save mode, the wireless power transmitterapplies different amounts of power to its power transmitter.

FIG. 8 illustrates histograms of amounts of power applied by a wirelesspower transmitter over time, according to an embodiment of the presentinvention.

For example, as illustrated in FIG. 8, the wireless power transmitterapplies second detection powers 801 and 802 and third detection powers811 to 815 to the power transmitter. More specifically, the wirelesspower transmitter applies the second detection powers 801 and 802 atsecond cycles in a second period of time and applies the third detectionpowers 811 to 815 at third cycles in a third period of time. AlthoughFIG. 8 illustrates the third detection powers 811 to 815 havingdifferent values, the third detection power 811 to 815 may have the samevalues.

The second detection powers 801 and 802 are set to drive the wirelesspower receiver, i.e., to drive the controller and communication unit ofthe wireless power receiver.

The wireless power transmitter applies the second detection powers 801and 802 and the third detection powers 811 to 815 to the wireless powerreceiver at second and third cycles, respectively. If the wireless powerreceiver is arranged on the wireless power transmitter, impedance viewedfrom a particular point of the wireless power transmitter changes. Thewireless power transmitter detects the change in impedance whileapplying the second detection powers 801 and 802 and the third detectionpowers 811 to 815. For example, the wireless power transmitter maydetect the change in impedance while applying the third detection power815.

Accordingly, referring again to FIG. 7, the wireless power transmitterdetects an object in step S707. If an object has not been detected instep S707, the wireless power transmitter maintains the power save modein step S705.

When an object is detected, e.g., by a change in impedance, in stepS707, the wireless power transmitter enters a low power mode in stepS709. In the low power mode, the wireless power transmitter appliesenough power to drive the controller and communication unit of thewireless power receiver.

For example, as illustrated in FIG. 8, the wireless power transmitterapplies driving power 820 to the power transmitter. The wireless powerreceiver receives the driving power 820 and drive the controller andcommunication unit. Based on the driving power 820, the wireless powerreceiver communicates with the wireless power transmitter in apredetermined scheme. For example, the wireless power receiver transmitsor receives data for authentication, and joins a wireless power networkhosted by the wireless power transmitter based on the data.

In step S711, the wireless power transmitter enters the power transfermode to transmit charging power. For example, the wireless powertransmitter applies charging power 821, as illustrated in FIG. 8, andthe charging power 821 is transmitted to the wireless power receiver.

The wireless power transmitter determines whether an error occurs in thepower transmit mode. The error may be a foreign object being placed onthe wireless power transmitter, a cross connection, over voltage, overcurrent, over temperature, etc. The wireless power transmitter mayinclude a sensing unit to measure over voltage, over current, overtemperature, etc. For example, the wireless power transmitter maymeasure a voltage or current at a reference point and determine that themeasured voltage or current meets the over voltage condition or the overcurrent condition if it exceeds a threshold value. Alternatively, thewireless power transmitter may include a temperature sensing unit tomeasure a temperature at a reference point of the wireless powertransmitter. If the temperature measured at the reference point exceedsa threshold, the wireless power transmitter determines that the overtemperature condition is met. Therefore, although FIG. 8 illustrates anerror of a foreign object being detected by the wireless powertransmitter, the error is not limited thereto, and the wireless powertransmitter may operate similarly for different types of errors, e.g., across connection, over voltage, over current, over temperature, etc.

If no error occurs in step S713, the wireless power transmittermaintains the power transmit mode in step S711. However, if an erroroccurs in step S713, the wireless power transmitter enters the latchfault mode in step S715.

For example, as illustrated in FIG. 8, the wireless power transmitterapplies first powers 831 to 835. While in the latch fault mode, thewireless power transmitter may output an indication of the error, e.g.,a lamp flickering and/or warning sound.

If it is determined that the object causing the error, i.e., the foreignobject or a wireless power receiver, has not been removed in step S717,the wireless power transmitter maintains the latch fault mode in stepS715.

However, if the object causing the error is removed in step S717, thewireless power transmitter re-enters the power save mode in step S719.

For example, as illustrated in FIG. 8, the wireless power transmitterapplies second powers 851 and 852 and third powers 861 to 865.

FIG. 9 is a flowchart illustrating a method of controlling a wirelesspower transmitter, according to an embodiment of the present invention.

Referring to FIG. 9, the wireless power transmitter applies chargingpower to a first wireless power receiver in step S901. In step S903, thewireless power transmitter detects a second wireless power receiverjoining in the wireless power network. In step S905, the wireless powertransmitter transmits charging power to the second wireless powerreceiver.

The wireless power transmitter may apply a total of charging powerrequired by the first wireless power receiver and the second wirelesspower receiver.

FIG. 10 illustrates histograms of amounts of power applied by a wirelesspower transmitter, according to the embodiment of FIG. 9. Specifically,FIG. 10 illustrates to the power transmissions in steps S901 to S905 ofFIG. 9.

For example, referring to FIG. 10, the wireless power transmittermaintains the power save mode in which it applies second detectionpowers 1001 and 1002 and third detection powers 1011 to 1015.Thereafter, the wireless power transmitter detects the first wirelesspower receiver and enters the low power mode to hold detection power1020. Subsequently, the wireless power transmitter enters the powertransmit mode to apply first charging power 1030. The wireless powertransmitter detects the second wireless power receiver and authorizesthe second wireless power receiver join in the wireless power network.The wireless power transmitter applies second charging power 1040, whichis equal to a total amount of power required by the first and secondwireless power receivers.

Referring again to FIG. 9, the wireless power transmitter detects if anerror occurs in step S907, while transmitting charging power to both ofthe first and second wireless power receivers. As described above, theerror may be a foreign object detected by the wireless powertransmitter, a cross connection, over voltage, over current, overtemperature, etc. If no error occurs in step S907, the wireless powertransmitter maintains application of second charging power 1040 in stepS905.

If an error occurs in step S907, the wireless power transmitter entersthe latch fault mode in step S909. For example, the wireless powertransmitter applies first powers 1051 to 1055 at first cycles, asillustrated in FIG. 10.

In step S911, the wireless power transmitter determines whether both thefirst and second wireless power receivers have been removed.

For example, the wireless power transmitter may detect a change ofimpedance while applying the first powers 1051 to 1055. Such detectionis made based on whether the impedance returns to its initial value.

If both the first and second wireless power receivers are determined tohave been removed in step S911, the wireless power transmitter entersthe power save mode in step S913.

For example, the wireless power transmitter applies the second detectionpowers 801 and 802 and the third detection powers 811 to 815 to thewireless power receiver at second and third cycles, respectively.

As described above, even when the wireless power transmitter appliescharging power to a plurality of wireless power receivers, it may stilldetermine whether a wireless power receiver or a foreign object isremoved when an error has occurred.

FIG. 11 is a block diagram illustrating a wireless power transmitter anda wireless power receiver, according to an embodiment of the presentinvention.

Referring to FIG. 11, the wireless power transmitter 1100 includes acommunication unit 1110, a Power Amplifier (PA) 1120, and a resonator1130. The wireless power receiver 1150 includes a communication unit1151, an Application Processor (AP) 1152, a Power Management IntegratedCircuit (PMIC) 1153, a wireless power Integrated Circuit (IC) 1154, aresonator 1155, an Interface Power Management IC (IFPM) 1157, a TravelAdapter (TA) 1158, which is a cable charging adapter, and a battery1159.

The communication unit 1110 communicates with the communication unit1151, based on a predetermined method, e.g., a BLE method. For example,the communication unit 1151 of the wireless power receiver 1150transmits a PRU dynamic signal having a data structure as shown in Table3 to the communication unit 1110 of the wireless power transmitter 1100.

Based on the received PRU dynamic signal, a power value output from thepower amplifier 1120 may be adjusted. For example, if an over voltage,an over current, or an over temperature is applied to the wireless powerreceiver 1150, the power value output from the power amplifier 1120 maybe decreased. If a voltage or current of the wireless power receiver1150 has a value less than a preset value, the power value may beincreased.

Charging power from the resonator 1130 is wirelessly transmitted to theresonator 1155.

The wireless power IC 1154 rectifies and DC-to-DC converts the chargingpower received from the resonator 1155. The wireless power IC 1154drives the communication unit 1151 or charges the battery 1159 with theDC converted power.

The cable charging adapter 1158 receives a cable charging terminal, suchas a 30-pin connector, a Universal Serial Bus (USB) connector, etc.,receives power supplied by an external power source through the cablecharging terminal, and charges the battery 1159.

The IFPM 1157 receives power applied from the cable charging terminaland outputs the resultant power to the battery 1159 and the PMIC 1153.

The PMIC 1153 manages the power wirelessly received or the powerreceived via cable, and the power applied to respective components ofthe wireless power receiver 1150. The AP 1152 receives power informationfrom the PMIC 1153 and controls the communication unit 1151 to transmitthe PRU dynamic signal to report the reception of the power information.

A node 1156 connected to the wireless power IC 1154 is also connected tothe cable charging adapter 1158. If the cable charging connector isinserted into the cable charging adapter 1158, a predetermined voltage,e.g., 5V, is applied to the node 1156. The wireless power IC 1154determines whether the cable charging connector is inserted into thecable charging adapter by monitoring the voltage applied to the node1156.

FIG. 12 is a signal flow diagram illustrating a permission procedure fora wireless power receiver, according to an embodiment of the presentinvention.

Referring to FIG. 12, a wireless power transmitter 400 transmits a PRUcontrol signal or a PRU control message to a wireless power receiver 450in step S1201. For example, the PRU control signal may include enableinformation, charging permission information, information about adetailed reason for standby for charging, etc. The PRU control signal istransmitted by the wireless power transmitter 400 to the wireless powerreceiver 450, after the wireless power transmitter 400 and the wirelesspower receiver 450 configure a network by exchanging static signals witheach other, as illustrated in FIG. 4.

Upon reception of the PRU control signal, the wireless power receiver450 identifies the charging permission information included in the PRUcontrol signal. If the PRU control signal includes information todictate standby for charging in a predetermined data field, the wirelesspower receiver 450 displays an indication that standby for charging isrequired in step S1202, e.g., as illustrated in FIG. 15. The wirelesspower receiver may also present a message allowing the user to select inadvance, whether or not to be on standby for charging, e.g., through areceiver charging application.

The user may or may not select standby for charging. In addition, nodetermination is made whether to be on standby for charging within apredetermined period of time, a default selection may be entered, e.g.,it is determined not to be on standby for charging.

As such, a determination about whether to be on standby for charging ismade in the wireless power receiver in step S1203, and the wirelesspower receiver sends the wireless power transmitter 400 informationabout the determination (standby-on or standby-off) in a PRU reportingsignal or a PRU reporting message in step S1204.

In step S1205, the wireless power transmitter 400 receives the PRUreporting signal from the wireless power receiver 450 and proceeds basedon the information about the determination (standby-on or standby-off).

For example, if the information about the determination included in thePRU reporting signal is standby-on, the wireless power transmitterperforms a process based on the wireless power receiver 450 being onstandby for charging. However, if the information about thedetermination included in the PRU reporting signal is standby-off, thewireless power transmitter terminates a connection with the wirelesspower receiver.

FIG. 13 is a flowchart illustrating an operating process of a wirelesspower transmitter, according to an embodiment of the present invention.

Referring to FIG. 13, the wireless power transmitter inserts chargingauthorization (or permission) information into the PRU control signal instep 1301, and transmits the resultant PRU control signal to acorresponding wireless power receiver in step S1302.

Upon reception of the PRU reporting signal from the wireless powerreceiver in return for the PRU control signal in step S1303, thewireless power transmitter checks content of the PRU reporting signal instep S1305. If the PRU reporting signal is found to have standby-on instep S1306, the wireless power transmitter performs a process based onthe wireless power receiver being on standby for charging in step S1308.

However, if the PRU reporting signal is found to have standby-off instep S1306, the wireless power transmitter terminates connection withthe wireless power receiver in step S1307. Optionally, after thedisconnection, the wireless power transmitter may enter the latch faultmode in step S1309.

If a PRU reporting signal is not received in step S1303, the wirelesspower transmitter regards the wireless power receiver as a log device instep S1304.

FIG. 14 is a flowchart illustrating an operating process of a wirelesspower receiver, according to an embodiment of the present invention.

Referring to FIG. 14, upon reception of the PRU control signal from thewireless power transmitter in step S1401, the wireless power receiverchecks the charging authorization (or permission) information includedin the PRU control signal in step S1402. If the charging authorizationinformation indicates that charging is permitted in step S1403, thewireless power receiver continues to perform the charging process withthe wireless power transmitter and receives wireless power from thewireless power transmitter in step S1404.

However, if the charging authorization information indicates thatcharging is permitted in step S1403 and that standby for charging isrequired in step S1405, the wireless power receiver starts a standbytimer S1407 and waits for a user to indicate whether to be on standby.If the user inputs standby-on before expiration of the standby timer instep S1408, the wireless power receiver sends the standby-on informationin the PRU reporting message in step S1411.

However, if the user inputs standby-off or indicated nothing by theexpiration of the standby timer, the wireless power receiver sends thestandby-off information in the PRU reporting message in steps S1411 andS1409, respectively.

If an indication that charging is not permitted is included in the PRUcontrol signal in step S1403 and standby for charging is not required instep S1405, the wireless power receiver terminates the connection withthe wireless power transmitter in step S1406.

FIG. 15 illustrates a standby screen of a wireless power receiver,according to an embodiment of the present invention.

Referring to FIG. 15, if the wireless power transmitter 400 transmits aPRU control message including information about charging authorizationto the wireless power receiver 450, the wireless power receiver 450receives the PRU control message and then displays a message asking theuser to select whether or not the wireless power receiver 450 should goon standby for charging.

When the user determines to have the wireless power receiver 450 to beon standby for charging, the user selects “yes” 1510 and waits forcharging. However, when the user determines not to have the wirelesspower receiver 450 be on standby for charging, the user selects “no”1502 and terminates connection of the wireless power receiver 450 withthe wireless power transmitter 400.

Fields of PRU control characteristics may be configured as shown inTable 3 and Table 4 below.

Table 3 shows data fields of the PRU control signal, i.e., PRU controlcharacteristics, and Table 3 shows bit fields for “enable”. For example,each characteristic value is set to be 5 octets long.

TABLE 3 Charac- Data teristic Description Direction Properties When usedEnables 1 PTU turn on, Mandatory “0” Disable PTU on “1” Enableindication etc. Permission 3 PRU is Mandatory “0” Not permitted inPermission PTU “1” Permission RFU 1

TABLE 4 7 6 5 4 3 2 1 0 Enable PRU Enable PRU Reduce power Invalid loadRFU RFU RFU output charge command indicator 1 = Enable 1 = Enable 00 =Maximum power 1 = Valid RFU RFU RFU 0 = Disable 0 = Disable 01 = 66% *PRECT_MAX 0 = Invalid; 10 = 33% * PRECT_MAX remain shut 11 = 2.5 W down

The PRU control message is a signal to be transmitted by the wirelesspower transmitter to control wireless charging of the wireless powerreceiver, which is transmitted from the wireless power transmitter tothe wireless power receiver, as illustrated in FIG. 4.

In the PRU control signal, “Enable PRU charge indicator” instructs thewireless power receiver to reach maximum power. In this regard, it setsthe wireless power receiver at 500 mW before the wireless power receiverreaches the maximum power.

In the PRU control signal, “reduce power” instructs the power of thewireless power receiver to be reduced.

Furthermore, a bit field for permission in Table 3 may be configured asshown in Table 5 below.

TABLE 5 Value (Bit) Description 0 Permitted without reason 1 =Permission, 0 = Not Permission 1 Denied with system error 3 described in1 = Permission, Section 5.2.8.7. 0 = Not (Cross-Connection case)Permission 2 Denied due to limited affordable power 1 = Permission, 0 =Not Permission 3 Permitted with waiting time due to 1 = Permission,limited affordable power 0 = Not Permission 4 Denied due to limited PTUMax Source 1 = Permission, Impedance 0 = Not Permission 5 Denied due tolimited PTU Max Load 1 = Permission, Resistance 0 = Not Permission 6Denied due to limited PTU Number of 1 = Permission, Devices 0 = NotPermission 7 Denied due to limited PTU Class support 1 = Permission, 0 =Not Permission 8 Denied due to limited PTU resonator 1 = Permission,design 0 = Not Permission 9 Denied due to limited H/W revision 1 =Permission, 0 = Not Permission 10 Denied due to limited Firmwarerevision 1 = Permission, 0 = Not Permission 11 Denied due to limitedProtocol revision 1 = Permission, 0 = Not Permission 12 Denied due tonon-certified device 1 = Permission, 0 = Not Permission 13 Denied due tonot supporting PRU Vrect 1 = Permission, min 0 = Not Permission 14Denied due to not supporting PRU Vrect 1 = Permission, max 0 = NotPermission 15 Denied due to not supporting PRU Vrect 1 = Permission,Target 0 = Not Permission 16 Denied due to not supporting 1 =Permission, Authentication 0 = Not Permission 17 Denied due to hardinterference 1 = Permission, 0 = Not Permission 18-23 RFU RFU

Table 6 and Table 7 show reactions of the wireless power receiver to thevalues, as shown in Table 5, which are included in the PRU controlsignal that the wireless power receiver receives. That is, the wirelesspower receiver displays a User Interface (UI) from the user perspectiveor performs operations with reference to received detailed permissioninformation as shown in Table 6 and Table 7 below.

Table 6 and Table 7 show PTU/PRU operations.

TABLE 6 Value UI (Bit) Description If PRU Receive Next Message 0Permitted without 1. Pop up Registration Confirm reason Message throughReceiving Phone UI 2. Show Confirmation through Phone Lamp (Red/Blue) 3.Indicate Confirmation through Phone Alarm 1 Denied with system 1. Pop upRegistration Confirm error 3 described in Message through UI for e.g.,Section 5.2.8.7. Phone 2. Display Indication that Connection with otherPTU Device is made (Cross- Connection case) 2 Denied due to limited 1.Display in Phone that there affordable power is No Sufficient Power fromTx PAD and Notify of Removal 3 Permitted with waiting 1. Pop up Messagein Phone to time due to limited be on Standby for Charging affordablepower 4 Denied due to limited 1. Display in Phone that Charging PTU MaxSource Efficiency may be limited Impedance 5 Denied due to limited 1.Display in Phone that Charging PTU Max Load Efficiency may be limitedResistance 6 Denied due to limited 1. Notify in Message that PTU PTUNumber of cannot Charge Exceeding Devices Number of Devices 7 Denied dueto limited 1. Display that PTU cannot Charge PTU Class support PRU 2.Display that PRU Category is not Supported 8 Denied due to limited 1.Display that PTU cannot Charge PTU resonator design PRU

TABLE 7 Value UI (Bit) Description If PRU Receive Next Message 9 Denieddue to limited 1. Pop up in Message that Some H/W revision Functions areLimited due to Low H/W version of PRU 2. Display in Phone an indicationthat Charging Efficiency may be Limited 10 Denied due to limited 1. Popup in Message that Some Firmware revision Functions are Limited due toLow Firmware version of PRU 11 Denied due to limited 1. Pop up inMessage that Some Protocol revision Functions are Limited due to LowProtocol version of PRU 12 Denied due to 1. Turn on Light in Tx PADnon-certified device Indicating non-Authentication Device (e.g., redlight flickering or alarming 5 times in a row) 2. Pop up Message ofWrong Cross Connection for User to Re-arrange the Device 13 Denied dueto not — supporting PRU Vrect min 14 Denied due to not — supporting PRUVrect max 15 Denied due to not — supporting PRU Vrect Target 16 Denieddue to not — supporting Authentication 17 Denied due to hard —interference 18-23 RFU —

In the following, charging standby operation mechanism (framemodification/reflection) will be described with reference to Tables 8 to10.

Table 8 illustrates information included in the PRU reporting messagetransmitted from the wireless power receiver to the wireless powertransmitter.

TABLE 8 Value (Bit) Description PRU's Message 3 Permitted with waitingtime due Send PTU Message that PRU is to be to limited affordable poweron Standby on Tx PAD Respond that it is on Standby and Request to holdConnection (Use PRU Control Characteristic) ↓ 7 6 5 4 3 2 1 0 Enable PRUEnable PRU Reduce power Invalid load PRU RFU RFU output charge commandWait indicator 1 = Enable 1 = Enable 00 = Maximum power 1 = Valid 1 = OnRFU RFU 0 = Disable 0 = Disable 01 = 66% * PRECT_MAX 0 = Invalid; 2 =Off 10 = 33% * PRECT_MAX remain 11 = 2.5 W shut down

The wireless power receiver keeps connection with the wireless powertransmitter by sending, to the wireless power transmitter, an indicationthat the wireless power transmitter is to wait for wireless charging inthe PRU reporting message. When the wireless power receiver will “wait”for wireless charging, the wireless power transmitter recognizes a loadchange on its charging pad.

FIG. 16 is a signal flow diagram illustrating a permission procedurebetween a wireless power transmitter and a wireless power receiver,according to an embodiment of the present invention.

Referring to FIG. 16, the wireless power transmitter (PTU) sends thewireless power receiver (PRU) information that standby for charging isrequired in the PRU control signal in step S1601, and then the wirelesspower receiver displays a message that standby for charging is requiredin step S1603, e.g., as illustrated in FIG. 15.

In step S1605, the user determines whether to have the wireless powerreceiver to be on standby for charging. In step S1607, the wirelesspower receiver sends the determination result (e.g., standby-on orstandby-off) to the wireless power transmitter in the PRU reportingsignal.

In FIG. 16, the wireless power receiver sends standby-on in the PRUcontrol signal in step S1607, and the connection between the wirelesspower transmitter and the wireless power receiver is maintained in stepS1609.

Thus, after a lapse of a certain period of time, when the wireless powertransmitter is able to charge the wireless power receiver, in stepS1611, the wireless power transmitter sends, to the wireless powerreceiver, information indicating that charging is enabled in the PRUcontrol signal. Upon reception of the PRU control signal, the wirelesspower receiver starts charging by turning a PRU load switch on.

Table 9 shows examples of several system error conditions.

TABLE 9 System Error Fault description 1 PRU over-voltage region 2 PTUco-location 3 PTU determines it has established a communication linkwith a PRU that is not in the PTU charge area 4

If a system error occurs in the wireless power receiver, the wirelesspower transmitter may hold information of the wireless power receiver insystem registration for greater than three seconds.

Table 10 shows an example of information of the wireless powertransmitter.

TABLE 10 Additional Origin Destination Required Required State State orOptional conditions Exceptions PTU PTU Required None At least one PowerConfiguration PTU Local Save Mode Fault PTU Low Power Mode PTU PowerTransfer Mode

According to the above-described embodiments of the present invention, amethod and apparatus are provided for charging a wireless power receiverin a wireless power transmitter of a wireless charging network.

With the method and apparatus, the wireless power transmitter sendscharging authorization information indicating whether the wireless powerreceiver is authorized for charging, via a PRU control signal, therebyefficiently controlling the charging of the wireless power receiver.

Further, the wireless power transmitter efficiently manages networkingwith various wireless power receivers within its range by receiving areporting signal from the wireless power receivers.

While the present invention has been shown and described with referenceto certain embodiments thereof, it will be understood by those skilledin the art that various changes in form and details may be made thereinwithout departing from the spirit and scope of the present invention asdefined by the appended claims and their equivalents.

What is claimed is:
 1. A method for permitting a wireless power receiverto be charged by a wireless power transmitter, the method comprising thesteps of: if the wireless power transmitter is not able to charge thewireless power receiver due to limited available power, generating afirst Power Receiving Unit (PRU) control signal including a permissionfield indicating that charging the wireless power receiver is permittedwith waiting time and transmitting the first PRU control signal to thewireless power receiver; and if the wireless power transmitter hasavailable power, generating a second PRU control signal including apermission field indicating that the wireless power receiver ispermitted to begin charging and transmitting the second PRU controlsignal to the wireless power receiver.
 2. The method of claim 1, furthercomprising receiving from the wireless power receiver a PRU reportingsignal including standby information indicating whether the wirelesspower receiver is on standby for charging.
 3. The method of claim 2,further comprising preparing for charging the wireless power receiver,if the standby information indicates that the wireless power receiver ison standby for charging.
 4. The method of claim 1, wherein transmittingthe first PRU control signal includes maintaining a connection with thewireless power receiver if the wireless power transmitter remains in apower transfer state of the wireless power transmitter.
 5. The method ofclaim 2, further comprising terminating a connection with the wirelesspower receiver, when the standby information indicates that the wirelesspower receiver is not on standby for charging.
 6. The method of claim 2,further comprising entering into a latch fault state, when the standbyinformation indicates that the wireless power receiver is not on standbyfor the charging.
 7. A control method of a wireless power receiver, themethod comprising the steps of: receiving, from a wireless powertransmitter, a first Power Receiving Unit (PRU) control signal includinga permission field indicating that charging the wireless power receiveris permitted with waiting time if the wireless power transmitter is notable to charge the wireless power receiver due to limited availablepower; determining whether to be on standby; generating a PRU reportingsignal including standby information indicating whether or not thewireless power receiver is determined to be on standby for charging;transmitting the PRU reporting signal to the wireless power transmitter;and receiving, a second PRU control signal including a permission fieldindicating that the wireless power receiver is permitted to begincharging if wireless power transmitter has available power.
 8. Themethod of claim 7, wherein determining whether to be on standbycomprises: querying a user of the wireless power receiver whether or notto be on standby; receiving an indication from the user in response tothe querying; and setting the standby information as standby-oninformation, if the indication from the user indicates to be on standbyfor charging.
 9. The method of claim 8, wherein determining whether tobe on standby further comprises setting the standby information asstandby-off information, if the indication from the user indicates notto be on standby for charging.
 10. The method of claim 7, whereindetermining whether to be on standby comprises: querying a user of thewireless power receiver whether or not to be on standby; failing toreceive an indication from the user in response to the querying, withina predetermined period of time; and setting the standby information asstandby-off information, based on the failing to receive the indication.11. A wireless power transmitter for wirelessly charging a wirelesspower receiver, the wireless power transmitter comprising: a powertransmitter configured to wirelessly transmit charging power to thewireless power receiver; a controller configured to generate a firstPower Receiving Unit (PRU) control signal including a permission fieldindicating that charging the wireless power receiver is permitted withwaiting time if the wireless power transmitter is not able to charge thewireless power receiver due to limited available power; and acommunication unit configured to transmit the first PRU control signalto the wireless power receiver, wherein the controller generates asecond PRU control signal including a permission field indicating thatthe wireless power receiver is permitted to begin charging, if thewireless power transmitter has available power and controls thecommunication unit to transmit the second PRU control signal to thewireless power receiver.
 12. The wireless power transmitter of claim 11,wherein the communication unit is configured to receive a PRU reportingsignal including standby information from the wireless power receiverindicating whether or not the wireless power receiver is on standby forcharging; and wherein the controller is configured to identify whetherthe wireless power receiver is on standby for charging from the PRUreporting signal.
 13. The wireless power transmitter of claim 12,wherein the controller prepares for charging the wireless power receiverif the standby information indicates that the wireless power receiver ison standby for charging.
 14. The wireless power transmitter of claim 12,wherein the controller keeps the connection with the wireless powerreceiver if it is found that the wireless power receiver is to be onstandby for charging.
 15. The wireless power transmitter of claim 11,wherein the controller maintains a connection with the wireless powerreceiver if the wireless power transmitter remains in a power transferstate.
 16. The wireless power transmitter of claim 12, wherein thecontroller terminates the connection with the wireless power receiver ifit is found that the wireless power receiver is not to be on standby forcharging.
 17. The wireless power transmitter of claim 12, wherein thecontroller turns into a latch fault state if it is found that thewireless power receiver is not to be on standby for charging.
 18. Awireless power receiver for being wirelessly charged by a wireless powertransmitter, the wireless power receiver comprising: a power receiverconfigured to receive charging power from the wireless powertransmitter; a communication unit configured to receive, from thewireless power transmitter, a first Power Receiving Unit (PRU) controlsignal including a permission field indicating that charging thewireless power receiver is permitted with waiting time when the wirelesspower transmitter is not able to charge the wireless power receiver dueto limited available power; a display unit configured to display amessage asking a user whether to be on standby; and a controllerconfigured to generate a PRU reporting signal including standbyinformation indicating whether the wireless power receiver is on standbyfor charging and to control the communication unit to transmit the PRUreporting signal to the wireless power transmitter, wherein thecommunication unit receives a second PRU control signal including apermission field indicating that the wireless power receiver ispermitted to begin charging if the wireless power transmitter hasavailable power.
 19. The wireless power receiver of claim 18, whereinthe controller indicates standby-on information in the PRU reportingsignal if standby for charging is selected by an input means from themessage on the screen.
 20. The wireless power receiver of claim 18,wherein the controller indicates standby-off information in the PRUreporting signal if standby for charging is not selected by an inputmeans from the message on the screen.
 21. The wireless power receiver ofclaim 18, wherein the controller indicates standby-off information inthe PRU reporting signal if standby for charging is not selected withina predetermined period of time from the message on the screen.